A power electronics including a transistor and a Schottky diode is frequently operated under high-power and high-temperature environments. Hence, III-nitrides having a high electric field and a large bandgap are often selected as an optimal choice for manufacturing a high-voltage and high-power power electronics including a transistor and a Schottky diode. Such power rectifier is applicable to high-power electronic elements including power distribution modules, power conditioning in large industrial motors, hybrid electric vehicles and switchers.
However, a Schottky diode and a transistor element manufactured from gallium nitride (GaN) usually suffer from unsatisfactory reverse leakage current and breakdown voltage. To achieve a low leakage and a high breakdown voltage, a solution of adding a guard ring having carriers in opposite polarities to a Schottky diode is provided in the prior art. Yet, on top of an additional masking process required for fabricating the guard ring, the guard ring also occupies an extra space such that a Schottky diode provided with a guard ring needs a larger space that disfavors a common goal of element miniaturization.
The US Patent Publication No. 20120025278 discloses a Schottky diode. The disclosed Schottky diode includes an ohmic contact layer formed by a semiconductor material, a metal layer serving as an anode, and a drift channel formed by a semiconductor material and formed between the ohmic contact layer and the metal layer. The drift channel includes a heavily-doped region neighboring to the ohmic contact layer, and a Schottky barrier is formed by the drift channel and the metal layer. When the Schottky diode is reversely biased, a pinch mechanism is applied to pinch the drift channel so that saturation or a leakage current between the metal layer and the ohmic contact layer is reduced.
Although the above Schottky diode does not need the design of a guard ring and is capable of reducing a leakage current as well as increasing a breakdown voltage of the Schottky diode, an overall manufacturing process is nevertheless made complicated due to the additional doping process for fabricating the heavily-doped region. Therefore, there is a need for an improved solution for providing a semiconductor element having a high breakdown voltage.